Negative electrode active material, negative electrode having the same and lithium secondary battery

Abstract

A lithium secondary battery includes a positive electrode having a positive electrode active material, a negative electrode having a negative electrode active material, a separator separating the positive electrode from the negative electrode, and an electrolyte. The negative electrode active material includes a graphite core particle, at least one metal particle located on the graphite core particle, and a polymer film coating the graphite core particle and the at least one metal particle. The polymer includes a polyimide- or polyacrylate-based polymer.

What is claimed is: 
     
       1. A negative electrode active material for forming a negative electrode active material layer on a negative electrode collector, comprising:
 a graphite core particle; 
 at least one metal particle on the graphite core particle; and 
 a polymer film substantially encapsulating the graphite core particle and the at least one metal particle, the polymer film configured to secure the at least one metal particle to a surface of the graphite core particle, 
 wherein the polymer film comprises a polymerization reaction product of a polyimide- or polyacrylate-based base polymer. 
 
     
     
       2. The negative electrode active material of  claim 1 , wherein the polyacrylate-based base polymer is selected from the group consisting of polymethylmethacrylate (PMMA), polyethylmethacrylate (PEMA), polybutyl methacrylate (PBMA), and mixtures thereof. 
     
     
       3. The negative electrode active material of  claim 1 , wherein the polymer film comprises a polymerization reaction product of the base polymer having a weight average molecular weight ranging from 1000 to 100000. 
     
     
       4. The negative electrode active material of  claim 1 , wherein the graphite core particle is selected from the group consisting of synthetic graphite, natural graphite, graphitized carbon fibers, graphitized mesocarbon microbeads, amorphous carbon, and combinations thereof. 
     
     
       5. The negative electrode active material of  claim 1 , wherein the metal particle comprises a material selected from the group consisting of Al, Si, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Ge, and mixtures thereof. 
     
     
       6. A negative electrode, comprising:
 a negative electrode collector; and 
 a negative electrode active material layer disposed on the negative electrode collector, the negative electrode active material layer comprising a negative electrode active material, a binder and a thickener, wherein the negative electrode active material comprises a plurality of graphite core particles, each graphite core particle comprises at least one metal particle in contact with a surface of the graphite core particle, and a polymer film coating the graphite core particle and the at least one metal particle, wherein the polymer film is configured to secure the at least one metal particle to the surface of the graphite core particle, the polymer film comprises a polymerization reaction product of a polyimide- or polyacrylate-based base polymer. 
 
     
     
       7. The negative electrode of  claim 6 , wherein the polyacrylate-based base polymer is selected from the group consisting of PMMA, PEMA, PBMA, and mixtures thereof. 
     
     
       8. The negative electrode of  claim 6 , wherein the polymer film comprises a polymerization reaction product of the base polymer having a weight average molecular weight ranging from 1000 to 100000. 
     
     
       9. The negative electrode of  claim 6 , wherein the graphite core particle is selected from the group consisting of synthetic graphite, natural graphite, graphitized carbon fibers, graphitized mesocarbon microbeads, amorphous carbon, and combinations thereof. 
     
     
       10. The negative electrode of  claim 6 , wherein the metal particle is selected from the group consisting of Al, Si, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Ge, and mixtures thereof. 
     
     
       11. A lithium secondary battery, comprising:
 a positive electrode having a positive electrode active material; 
 a negative electrode having a negative electrode active material, a binder and a thickener, the negative electrode active material comprising a plurality of graphite core particles, each graphite core particle comprising at least one metal particle on the graphite core particle, and a polymer film substantially encapsulating the graphite core particle and the at least one metal particle, the polymer film comprising a polymerization reaction product of a polyimide- or polyacrylate-based base polymer, the polymer film being configured to secure the at least one metal particle to a surface of the graphite core particle; 
 a separator separating the positive electrode from the negative electrode; and 
 an electrolyte. 
 
     
     
       12. The lithium secondary battery of  claim 11 , wherein the polyacrylate-based base polymer is selected from the group consisting of PMMA, PEMA, PBMA, and mixtures thereof. 
     
     
       13. The lithium secondary battery of  claim 11 , wherein the polymer film comprises a polymerization reaction product of the base polymer having a weight average molecular weight ranging from 1000 to 100000. 
     
     
       14. The lithium secondary battery of  claim 11 , wherein the graphite core particles are selected from the group consisting of synthetic graphite, natural graphite, graphitized carbon fibers, graphitized mesocarbon microbeads, amorphous carbon, and combinations thereof. 
     
     
       15. The lithium secondary battery of  claim 11 , wherein the metal particle is selected from the group consisting of Al, Si, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Ge, and mixtures thereof. 
     
     
       16. The lithium secondary battery of  claim 11 , wherein the electrolyte comprises a non-aqueous organic solvent and a lithium salt. 
     
     
       17. The negative electrode active material of  claim 1 , wherein the metal particle is present in a range of 3 wt % to 10 wt % based on the total weight of the negative electrode active material.